Tony Finch [mailto:[EMAIL PROTECTED]] wrote:
> Nik Clayton <[EMAIL PROTECTED]> wrote:
>>
>> I thought that 127/8 was the "local net", and that
>> packets sent to any of those addresses would go via
>> the loopback interface. That seems to be how Linux
>> and Windows 98 do things (the only systems I can
>> check this on at the moment). Assuming that's the
>> case, why does FreeBSD only add a a host route to
>> 127.0.0.1, and not a network route for 127/8?
>
> I did some further investigation to see how old this
> oddity is and it seems to be the way BSD has always
> handled the loopback interface. There's an explicit
> exclusion in the interface initialization code in in.c
> that gives loopback interfaces a host route instead of
> the network route that a normal interface gets and it's
> been that way for 15 years.
I always thought it was a great waste of network address
space to devote an entire class A network to a single
loopback address. An idea I got from a co-worker a while
ago was to allow the 127.* (or some smaller subnet of 127)
to be devoted to "intra-box addresses", for example:
1. A cluster of devices/slots within a chassis
2. A parallel processing machine
3. A multi-processor computer/device
All of the above may have inter-processor communications
that do not need to leave the chassis. Analogous to how
the 192.168.* (RFC1918) addresses are used for intranets,
these addresses wouldn't be allowed to be seen by the outside
world (i.e. outside the "chassis"), but would permit internal
IP communication without having to waste (and configure) a
"real" IP net number. If these devices needed to get to the
outside world, they could use NAT (again, analogously to the
RFC1918 case).
Regards,
Eric
--
Eric Peterson
[EMAIL PROTECTED] (805) 370-3046
PGP: http://pgp5.ai.mit.edu:11371/pks/lookup?op=get&search=0x4DA8EEF1
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